I have been using heavy weight for over a year. My routine is two set every other day, starting with the 40 lbs and increasing the weight 10 lbs at a time until I get to the 70 lbs. Each time I add the 10 lbs I hold the weight for 30 seconds then add another 10 lbs. When I get to the 70 lbs I do the reverse going back down to the 40 lbs. It took me around 6 month before I was able to handle the 70 lbs. I have got as far as 80 lbs but for only 15 seconds. My goal is to reach 100 lbs sometime this year.
You must have a fast system to attach the weight every 30 seconds with the rest of the weight hanging. I like passive hanging for longer time so I can do desk tasks, but yours seems to be more effective in less pe time.
I, can, I can, I can not, can not compute..